2 cancer drugmakers just presented key data about how new treatments work in lung cancer — and the markets picked a winner (MRK, BMY)

Two cancer drugmaker rivals presented data on Monday about how combinations of their drugs, which harness the body’s immune system to treat cancer, worked in treating a common form of lung cancer compared to traditional chemotherapy.

Merck showed that its drug Keytruda in combination with chemotherapy cut the risk of death in lung cancer patients in half.

Bristol-Myers Squibb, which makes a competing immunotherapy, Opdivo, showed that its drug in combination with Yervoy, another immunotherapy, managed to keep patients with tumors that had a certain amount of mutations from getting worse for a longer period of time than those treated with chemotherapy.